In magnetic storage devices such as hard disk drives (HDD), read and write heads are used to magnetically read and write information to and from storage media. In a HDD, data may be stored on one or more disks in a series of adjacent concentric circles which may be referred to as data tracks. A HDD may include a rotary actuator, a suspension mounted on an arm of the rotary actuator, and a slider bonded to the suspension to form a head gimbal assembly (HGA). In a traditional HDD, the slider carries a write head and read head, and radially floats over the surface of the storage media, e.g., a disk, under the control of a servo control system that selectively positions a head over a specific track of the disk. In this one read head (reader) configuration, the reader is aligned over the center of a track for data read back.
As HDD storage capacities have increased, the data track separation has decreased and the density has increased. Smaller reader dimensions are required to meet these requirements of increasing track density and linear density. In tunneling magnetoresistance (TMR) readers, for example, this may involve decreasing the volume of the antiferromagnetic (AFM) layer. This reduction in volume reduces the blocking temperature distribution (TbD) and the pinning magnetic field strength (Hex) in the TMR reader, thereby worsening the thermal stability of the pinned layer. Accordingly, as the size of the TMR reader decreases, the pinning strength or exchange field needs to be increased to keep the pinned layer stable. Prior processes have focused on heating the AFM layer after its deposition to improve the pinning field. However, this process does not improve the blocking temperature.